The lights are back on the normal cycle now (which will only matter once lights are out tonight) and pH is back near normal. A fair amount of cloudiness is still there, and I'm doing small frequent water exchanges. The BTA just concerns me because it's completely under a rock, blocking it from the light. My wife checked it out with a flashlight, and it opened up a little in response to the light... but showed no inclination to move out of the dark.